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11 Dec 2005, 09:10

gamjatang wrote:

The sum of integers from 1 to n (inclusive) is n(n+1)/2.What is the sum from 50 to 100 (inclusive) ?

It seem s like i saw this problem on this Forum already!
Anyways My answer is 3825
Sum from 1 to 50 is 50(50+1)/2=25(51)
Sum from 1 to 100 is 100(101)/2=50(101)
Sum from 50 to 100(liitle trap here I guess) is 50(101)-25(51)
50(101)-25(51)=25(2(101)-51)=25*151=3775
Should be 3775 if my math is correct